The temps are very low and so solder fittings will work, they also serve to keep the weight down by reducing the number of heavy brass fittings needed.
My cell produces 1 lpm so the standard mig tip will need to be made smaller and we will cover that mod later on.
Step 1: Parts and Exploded View
- 6 inches 15mm copper tube
- 1" section between stopend and elbow.
- 1 ¼ " section between the coupler and the ball valve.( length is 30mm but 32mm seats well)
- remaining approx 4" between the elbow and ball valve.
- 15mm copper stopend.
- 15mm copper 90 ° elbow.
- coupler FIxC 15mm x ½ "
- ½ " BSP hosetail which is a standard LP gas fitting.
- mini ball valve compression fittings on both ends.
- mig welder tip either 0.8mm or 0.9mm which will be modified.
- a brass nut M6x1.9 for the mig tip.
Step 2: The Torch Tip
It’s easier to first drill and tap the copper stopend and brass nut seperately and then insert a SS bolt to line the parts up when soldering, this way the ss bolt can be easily removed afterwards once all the soldering is finished.
Don’t solder with the copper mig tip in place because you won’t be able to remove it again.
I had heard mig welder tips can be made smaller by tapping a ball bearing on top. It seems odd that forcing a ball bearing down would make the hole smaller, but the copper cant spread outwards and has nowhere else to go so it constricts thereby reducing the orifice diameter which works well.
The smallest mig tip is 0.6mm which was unobtainable, I have used both the 0.9mm and the 0.8mm and managed to get the hole size down to 0.45 mm which is the size of some stainless steel leader tooth proof fishing wire I use for replacing cheese slicer wire.
Step 3: Closing Bits
I used a M6 washer which I then had to grind down to fit inside the copper pipe.
Its very convenient to be able to shut off the gas at will without constant banging from flashbacks, however...
Don’t forget to switch off power to the cell once you have shut the ball valve, failure to do so will cause pressure buildup which could lead to leaks, explosions and equipment damage.